High-voltage circuit interrupter



Jam Mp E949,

R. H. ARLE Na HIGH VOLTAGE CIRCUIT INTERRUPTER Filled Jan. 29, 1.944

5 Sheets-Sheet l INVENTUM ,FAM/f ffy/PLE /fa/zm HAMA/wav um HIJWQ ATTO/PNE?.

18 i949t R. H. EARLE m mm HIGH VOLTAGE CIRCUIT INTERRUPTER Filed Jan. 29; 1944 $5 Sheets-.Sham 2 Jan@ i949. H. @ARMS ma HIGH VOLTAGE CIRCUIT INTERRUPTER shams-sheet 5 Filed Jan. 29, 1944 1 A NX Patented Jen. 18, 1949 HIGH-VOLTAGE CIRCUIT INTERRUPTER Ralph H. Earle, Wauwatosa, and Roald H. Amundson, Milwaukee, Wis., assignors to Line Material Company, South Milwaukee, Wis., a

corporation of Delaware Application January 29, 1944, Serial No. 520,180

l1 Claims.

heavy duty, drop-out circuit interrupter in which means are employed, such as a tube for instance, which provides an arc channel with a fusible link located in the arc channel, .and to provide means for extending the arc incident to rupture of the fuse link on overload and for drawing the arc into proximity to material adapted to evolve or liberate gas when acted upon by an arc to thereby produce a blast of gas axially of the arc channel to extinguish the arc, the construction being such that after the circuit has been interrupted within the arc channel the device drops out of circuit to an inoperative position.

Further objects are to provide a circuit interrupter which is so constructed that it will eectively interrupt the circuit for a relatively small overload or for a relatively large overload or for any intermediate value of overload with equal certainty of operation in each case, and which is so made that the building up of excessive pressure in the arc channel is prevented.

In greater detail, further objects of this invention are to provide a high voltage, heavy duty fuse construction in which an` expellable apertured plug is provided through which a blast of gas is projected to extinguish the arc upon rupture of the fuse link on moderate overloads with the plug so arranged that it is expelled on heavy overloads to provide a larger discharge passageway for the gas to thereby prevent the building up of excessive pressure in the device.

For one form that the invention may take, further objects are to provide a fuse construction in which means are provided for liberating arc extinguishing gas in one portion of the fuse tube to provide a violent blast of arc extinguishing gas which passes outwardly from the adjacent end of the fuse tube and to provide for the normal action of an expulsion fuse construction for the other portion of the device, and in addition to the dual action hereinabove set forth, to provide for the quick mechanical withdrawal of any remaining portion of the fuse link from the fuse tube.

For another form that theinventlon may take, further objects are to provide a fuse construction in which a blast of gas is employed for extinguishing the arc, in which plunger or other means withdrawn inwardly of a fuse tube by spring means is employed for leading the arc into proximity to material adapted to evolve gas when acted upon by an arc, means being provided for denitely limiting the travel of the plunger or other means to a predetermined length of path, the construction being such that the spring means is housed within a tube and is protected from the are and from any gas incident tothe arc.

In certain forms that the invention may take, further objects are to provide a fuse construction in which not only an apertured expellable plug is provided which may be expelled under high pressure internally of the device resulting from very heavy overloads, but in which in addition to this though the adjacent end of the fuse tube is closed by a cap, such cap is weakened along a. predetermined zone so that a portion of the cap is freely blown from the remainder of the device to provide free venting means, the portion so blown from the device providing an aperture large enough to permit the passage therethrough of the expellable plug.

For several forms of the invention, further objects are to so construct the interrupter that renewal or refill units carrying material adapted to evolve gas when acted upon by an arc may be substituted for the used units so that the major portion of the interrupter may be used over and over again.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a side elevation showing one form of the apparatus, such view showing the interrupter in circuit closed or operative position.

Figure 2 is an enlarged view of the fuse tube removed from the remainder of the apparatus, such view being partly in section and partly broken away.

Figures 3, 4 and 5 are fragamentary sectional views showing further forms of reill devices.

Figure 6 is a fragmentary view showing a further form of the invention.

Figure 'l is a view taken at right angles to Figure 6 and partly in section.

Figure 8 is a View of a fuse tube, partly broken away and partly in section, showing a further form of the invention.

Figure 9 is a view from the lower side of the member to which the lower end of the retracting spring of Figure 8 is attached.

audaci Figure 10 is a view, partly in section. showing another manner in which the arc extinguishing material may be furnished.

Referring to Figure 1, it will be seen that the device comprises upper and lower stationary terminals indicated generally by the reference characters I and 2 which are carried by suitable insulators 3 and 4, respectively, which in turn are supported from a suitable supporting member 5. A fuse tube 6 is pivotally supported from the lower terminal 2 and is provided with an upper terminal 1 having outwardly projecting members or pins 8 on opposite sides thereof. The upper stationary terminal I may be constructed as set forth in detail in the patent to William O. Schultz No. 2,357,772 of September 5, 1944, for Cut-out construction, and may comprise a pair of spring arms 9 which are pivotally supported by a stationary member I and bear against oppositely disposed, downwardly slanting cam portions II forming a portion of the stationary member I0. The spring arms are provided with downwardly depressed portions I2 and with outwardly and upwardly slanting guiding portions I3. Normally the projections 8 of the terminal 1 of the fuse tube are hooked behind the downwardly depressed portions I 2 of the spring arms 9. The lower stationary terminal 2 may be formed in the manner of a housing as indicated and may be provided with a pair of hook like supporting portions I4. The lower stationary terminal also includes a relatively heavy contact spring I5.

A fuse link is provided within the fuse tube 6 and the flexible leader I6 thereof extends outwardly through the lower open end of the fuse tube, as shown most clearly in Figure 2.

The lower portion of the fuse tube 6 has rigidly clamped thereto a sleeve like member I1 which 4 and fuse link clamping lever forms the subiect matter of the United States patent of William O. Schultz Number 2,378,109 of June 12, 1945, for Fuse constructions.

It is apparent that when the fuse link is ruptured, the main lever 20 is no longer held in the position shown in Figures 1 and 2 and it rocks downwardly pivoting about the trunnions 2I. This moves the lower end of the fuse tube downwardly and outwardly and allows the projecting portions 8 of the upper contact 1 of the fuse tube to disengage themselves from thelatching spring arms 9, such spring arms, however, following the fuse tube downwardly for a predetermined distance and being arrested in their downward motion by means of projections 28 at the lower end of the cam portion II of the stationary part of the stationary contact I. The fuse tube is now free to rock outwardly and downwardly to inoperative position.

The fuse tube is provided with a channel therethrough indicated by the reference character 2l and this channel has an enlarged portion 3l. Within this enlarged portion a fiber sleeve 3| is positioned. The liber sleeve iscarried by an outer metal sleeve 32 which has a portion 33 spun into a groove surrounding the fiber sleeve 3l. outer metal sleeve 32 is provided with a flange 34 which rests upon the upper edge of the upper terminal 1 of the fuse tube 6. A Bakelite cap 35 is screwed onto the upper terminal 1 of the fuse tube and has an annular groove 36 formed is provided with a rearwardly and downwardly projecting arm I8 pivoted as indicated at I9 between a pair of arms formed integrally with the main supporting lever 2|). This main supporting lever 20 is provided with a pair of trunnions 2| removably supported by the hook like portions I4 of the lower stationary terminal 2 and is provided with a rearwardly projecting portion 22 which normally engages the contact spring I5.

The main lever 20 carries a quick acting flip-out or fuse link extracting lever 23 which is pivotally mounted on a pin 24 carried by the main lever. The main lever has an outwardly extend-l ing portion 25. A fuse link clamping lever indicated by the reference character 26 is also pivoted on the pin 24. A spring 21 urges the flip-out lever or fuse link extracting lever 23 and the fuse link clamping lever 26 in opposite directions. The exible leader I6 is positioned in a grooved portion of the quick acting fuse link extractor or illpout lever 23 and passes around the outer end thereof and is clamped between the fuse link clamping lever 26 and the extension 25.

When the fuse link is ruptured, as will be described in greater detail hereinafter, the quick acting dip-out lever 23 extracts any remaining portion of the fuse link in a quick manner and rocks in a counterclockwise direction under the influence of the spring 21. The flip-out lever 23 and the fuse link clamping lever 26 areso constructed that they have interengaging portions which come into engagement when the flip-out lever has rocked a predetermined distance so that thereafter the fuse link clamping lever 26 and the flip-out lever 23 rock as a unit and release the leader I6 of the fuse link.

The particular construction of flip-out lever therein to provide a central portion 31 which is adapted to be blown outwardly upon rupture o f the fuse link. The fuse link includes the flexible leader I6 hereinbefore mentionedand a rod like retractable member 38 which is secured to the leader I6 at its lower end and at its upper end is secured to the fusible section 39 and strain wire 40 of the fuse link. The upper end of the fusible section and strain wire are secured to a rivet or button like member 4I which in turn is secured to a metal inverted cup like member 42. The cup like metal member 42 is provided with a plurality of resilient fingers 43 separated by slits as indicated in Figure 2 and these ngers 43 slidably nt within the upper portion of the metal sleeve 32, Gas liberating or evolving material such as the liquid 44 is carried within an annular rupturable container 45 which may, if desired, be made of glass. This container is hermetically sealed and has approximately an elongated torus shape. The retractable rod 38 freely passes through the central opening. The lower end of the container 45 is supported from a plug 46 screwed into the lower end ofthe ber sleeve 3i being preferably separated therefrom by means of a small cork washer 41. The upper end of theilber sleeve 3l has screwed thereinto a ber sleeve 43 and a cork washer 49 is interposed between the sleeve 4l and the container 45. An expellable plug 60 `formed of fiber is carried within the aperture section and the rod 33 is suddenly drawn downwardly due to the quick acting flip-out or fuse ex- The j audaci tractlng lever 22.

the gas evolving material and ruptures the container 45. The material evolves a quantity oi. arc extinguishing gas which is projected upwardly through the expellable plug 50. The central portion 31 of the cap is blown on together with the inverted cup-shaped metal member 42 and the violent outward blastl of gas acts to extinguish the arc. In addition to this, it will be seen that` as the rod or plunger 4B is drawn downwardly if the arc should persist and extend into the arc channel 29, not only the extinguishing action of the blast of gases from the material 44 is provided but in addition to that the normal expulsion action of the device occurs within the portion 29 of the arc channel and therefore there is this dual action that can take place in the event the arc follows theplunger into the portion 29 of the arc channel.

t is to be noted that when the iuse link extracting lever 23 quickly moves down under the influence of the spring 21, a portion thereof nally engages the clamping lever 26 and rocks such clamping lever downwardly as a unit with the flip-out lever. thus freeing the leader I6 and allowing any remaining portion of the fuse link g, not only to be withdrawn from the-tube 6 but to be thrown therefrom.v When the fuse link has ruptured, the main lever 20 is released and the fuse tube executes drop-out motion as hereinbefore described.

Ii a very heavy overload occurs, considerable pressure will build up beneath the expellable plug B and such plug will blow outwardly, thereby providing a larger bore through which the blast of arc extinguishing gas may pass thus preventing the building up of excessive pressure within the arc channel. Otherwise the action is the same as that described hereinabove for moderately heavy overloads. v

In refusing, the fuse tube is removed from the hook like supporting members I4, see Figure l, and is refused by unscrewing the remaining portion of the cap 35 and removing the fiber sleeve li and the metal sleeve 32. Thereafter a refill unit is positioned. The refill units comprise the. sleeve 3l and all of the associated parts including the metal sleeve 32 and the cap 42 as well as a new container 45 and composite fuse 1ink. This refill unit is readily positioned and the leader passed through the fuse tube 6 and secured in place between the clamping lever 26 and the projecting portion 25. Thereafter a new Bakelite cap 35 is screwed into place. The fuse tube 6 is then positioned with its trunnions 2l supported by the hook like members I4 and is rocked upwardly into position. ItI is to be noted that an eyeleted manipulating portion 5| is provided which is integral with the upper terminal 1 and such portion may be engaged by the switch stick when it is desired to rock the fuse tube 'back into place.

The material adapted to evolve gas when acted upon by the arc as indicated by the reference character 44 may be any suitable liquid such as carbon tetrachloride, methylene chloride or chloroform, or any other suitable material. As will appear as the description proceeds other material can be employed.

The reiill unit may take other forms from that shown in Figure 2. For instance as shown in Figure 3, the refill unit may have the retractable plunger 52 extend only approximately through the container 53. In this case the fusible section and the strain wire indicated respectively at 54 and 5l extend through the expellabie plug Il. Otherwise the construction is the same as that previously described. In the structure shown in Figure 2 the arc is formed above the plug 50 and is drawn downwardly through the plug into proximity to the arc evolving material. In Figure 3 the arc is formed within the plug 56 and is drawn downwardly into proximity to the arc evolving material.

The arc evolving material may be in the form of compressed apertured disks indicated at 51 in Figure 4 and these disks may be carried within a fiber sleeve 58 whose lower end is closed by means of an apertured, screw threaded plug 5S. The retractable rod 60 extends through all of the disks 51 of the gas evolving material and at its upper end passes through the expellable plug 5i, such plug being frictionally held within the liber sleeve 62, which latter is screwedinto the ber sleeve 58. The strain wire 53 and the fusible section E4 may extend laterally and upwardly from the upper end of the retractable rod 5S and are attached at their outer ends to the outer metal sleeve 65.

The disks 51 may consist of compressed boric acid or other suitable material.

It is also clear that the arc evolving material could be in the form of a powdered material as indicated by the reference character 66 in FigureV l0. In this case the powdered material is carried within a waxed paper container 81 which has annular fiber ends 68. Silicio acid, gunpowder or other suitable powdered material could be used. In the event the container shown in Figure 10 is used, it merely replaces the container of Figure 2, the length and size of the container of course being properly proportioned.

Figure 5 shows a further form of refill device.

` In this form of refill device the container 69 may be a simple form of glass bottle which contains the liquid 10 of the type hereinbefore described. It is carried within the enlarged upper bore 1l of a fiber sleeve 12. The upper end of the fiber sleeve receives the apertured and threaded plug 13. The outer metal sleeve is indicated by the reference character 14. It is to be noted that the sleeve 12 has a constricted opening 15 immediately below the enlarged upper opening ll and that/this constricted opening joins a larger opening 16 by means of a downwardly flaring opening Tl. The flexible leader is indicated by the reference character 18 and it is joined by means of the fusible section 1S and strain wire 8D to a conducting strip 8l which is positioned to the side of the container 69 and is electrically connected at its upper end to the metal sleeve 14. With this type of construction the discharge of gas is downwardly through the constricted opening 15 through the expanding portion 11 to the enlarged opening 16 and downwardly through the remainder of the arc channel. When this type of reilll device is employed, a permanently closed cap such as shown in the upper end of Figure 8 is employed and the cap is not adapted to be ruptured and expelled upwardly but is to remain intact during the voperation of the device as it is desired to have the gas discharge wholly in a downward direction when this type of refill device is employed. The bottle or container B9 employed in Figure 5 is a simple round type of bottle.

In the event a ilat type of bottle or container is employed as 'indicated by the reference character 82 in Figures 6 and 7, such bottle is adapted to seat on the lower shouldered portion 83 of an enlarged opening I4 formed in the upper end oi 7 the tube 89. The remainder of the arc channel is smaller as indicated at 09. In this form of the invention two conducting strips indicated at 91 are employed and are positioned on each side of the flat bottle 92. They are carried by a tting 99 which receives the screw threaded member 89 attached to the upper end of the exible leader 90. The upper ends of the conducting strips 81 vided with a weakened portion 90 and is adapted to have its central portion 90 blown outwardly therefrom. Also in this form of the invention a shouldered ber sleeve 91 is positioned in the upper end of the opening 84 of the fuse tube and ||9 which is'provided with a rearwardly project, ing arm |20 pivoted as indicated at |2|' to the main lever IM. It is apparent. therefore, that when' the fuse link is ruptured, the main lever lll moves downwardly and moves the lower end of the fuse tube |00 downwardly and outwardly allowing the upper end to detach itself from the spring arms of the upper stationary contact, the fuse tube thereafter executing drop-out motion.

The ber sleeve |01 carries an elongated, torusshaped, hermetically sealed container |22 of glass or other suitable material Within which material such as a liquid |23 is carried, the material being adapted to evolve gas when acted upon by an arc, the arc rupturing the container |22. The liquid may be carbon tetrachloride, methylene chloride or chloroform, or any other suitable material.

' The upper end of the tube |01 is closed bymeans is held in place on the terminal 9|. 'I'he expellable ber plug is indicted at 98.

In this form of device there are no rell units furnished for installation in the field. Instead'an entire new fuse tube is furnished. This form of 4the invention shown in Figures 6 and 'I is primarily intended to show a manner of using a at type of bottle or container within which the liquid 99 adapted to evolve gas when acted upon by the arc is carried. In this form of the inven tion the blast of arc extinguishing gas is upwardly through the apertured expellable plug 98, the central portion 96 of the Bakelite cap having been blown outwardly upon rupture of the fuse link. There is also a downward blast of gas which risses downwardly through the restricted channel In the form of the invention shown in Figure 8 the. fuse tube is indicated by the reference character |00. It is provided with an upper terminal |'0| which receives the screw threaded metal cap |02. The upper terminal is provided with outwardly projecting members |03 corresponding to the members 8 of Figure 1.

The fuse tube has a uniform bore |04 throughout its major portion. The lower portion of the bore, however, is enlarged as indicated at |05 and terminates in a shoulder |09. 'Within the enlarged portion |05 of the bore a ber tube |01 is positioned. This ber tube is rigidly carried by means of a metal sleeve |09 which has a portion spun into interlocking engagement with the ber sleeve. The metal sleeve |08 is provided with a flange |09 which is seated against the lower end of the tube |00. It is held in place by means of a threaded metal nut |0. Within the lower end of the metal sleeve |08 a metal cap is slidably positioned. It is preferably provided with a plurality of resilient fingers l| i2 separated by slots. It is connected by means of a exible leader v| i3 with a fuse link extracting lever III, the leader I3 being held in fplace by means of a thumb nut H5. The lever ||4 is provided with a rounded lower portion ||6 beneath which the leader l| |3 passes.

The lever III has a pair oi' rearwardly projecting arms which are provided with trunnions ||1 adapted to seat within the hook like supports |0 of Figure l. It has a rearwardly projecting portion ||9 adapted to engage the lower contact spring Ii of Figure 1. The lower end of the fuse tube is rigidly attached to a sleeve like member of a screw threaded apertured plug |24. The lower end of the ber sleeve or tube |01 receives the threaded ber sleeve |25. Between the container |22 and the sleeve |20 and the plug |26 cork or similar washers are positioned as indicated'in Figure 8.

The ber sleeve |25 carries the expellable plug |26 of ber which has a reduced portion out of contact with the sleeve |25 and an enlarged portion slidably held within the sleeve so as to allow the plug |26 to be blown from the ber sleeve under very heavy overloads. v

A retractable plunger |21 freely passes through the container |22 and through the plugs |26 and |24. Its lower end is attached to the exible leader ||3 and the metal cap by means of a4 strain wire |20 and a fusible section |29. The upper end of the retractable metal plunger |21 is threaded and is received within a fitting or head |30. This head is provided with a flange |3| integral or otherwise rigidly secured thereto. The

flange approximately ts the larger bore |05 and means of the flexible leader |34. The upper head,

|33 is provided with a reduced externally and internally threaded portion |35 and receives the internally screw threaded metal washer |36. The metal washer |36 is rigidly clamped against the upper terminal |0| by means of the metal screw cap |02.

The ber sleeve |01 together with the container |22 and the associated parts including the metal cap and the flexible leader ||3 constitute a rell unit and lit isto be noted that the refill unit may be easily attached to the lower head |30 by `screwing the upper end of the retractable plunger |21 into the internally threaded lower head |30. In order to keep the plunger |21 from turning vwith reference to the sleeve |01 during this operation, it is provided with a., transverse pin |31 which seats Within a slot formed in the upper portion of the plug |24.

When an overload of moderate magnitude ockspring |32.

tion l of the upper head |33 slightly above the 9. |02, thus leading the arc into proximity. to the gas evolving material |23 and rupturing the container |22. A violent blast of arc extinguishing gases is generated and blows outwardly through the restricted aperture in the expellable plug |20 and extinguishes the arc.- The main lever lll rocks downwardly and moves the lower end of the fuse tube downwardly and outwardly and allows the fuse tube to drop out of position as hereinbefore described. It is to be noted particularly that the upward stroke of the retractable plunger is deilnitely limited by the stop means provided by the flange |3| and the shoulder |08.

. It is preferable to provide cut-outs |38 in the flange Itl to allor.l free passage of air and to prevent retardation of the upward motion of the plunger it?.

If a heavy overload had occurred, the operation is the same as hereinabove described except for the fact that the expellable plug |26 is blown out from the lower end of the tube |25 and a larger aperture is provided for the discharge of gases. This prevents the building up of excessive pressure within the device even under very heavy overloads.

It is to be understood that in all forms oi' the invention the cori: washers on opposite sides of the container are merely cushioning washers and are very thin and are immediately destroyed or blown outwardly during the operation of the apparatus under overload.

The reason for detachably coupling the upper head |33 with the metal washer |36 is to facilitate reloading of the device.

In refusing the device, the operator removes the cap |02 and unscrews the washer |30 from the upper head |33. Thereafter the operator unscrews the old rod |21 from the head |30 and the refill unit is thereafter attached to the lower head by screwing the rod 21 of the new unit into the lower head |3 Thereafter the operator screws the lower end of a threaded rod, not shown, into the internally threaded portion of the reduced part |35 of the upper head |33 and passes this rod upwardly through the fuse tube and passes the rod through the metal washer |30. .He then draws the rod upwardly and as soon as the flange |09 of the refill unit is seated against the lower end of the fuse tube |00, he continues drawing the rod upwardly and thus extends the When he has drawn the upper porupper end of the fuse tube, he screws the metal washer |36 onto the reduced portion |35 and allows the washer |36 to come to rest against the upper terminal |0| of the fuse tube. Thereafter he replaces the threaded cap |02 at the upper end of the i'use tube and the nut ||0 at the lower end of the fuse tube. He then attaches the flexible leader to the lever i4 by means of the thumb nut ||5 and the device is then ready to be reposltioned and rocked back into operative position.

It is to be noted that in all forms of the invention the drop-out fuse tube is adapted to be removed and repositioned by means of a switch stick and after being repositioned is rocked into operative position by means of the switch stick.

In all forms of the invention it is apparent that the fuse tube may be made of fiber or may be made of Bakelite lined with fiber in a well known manner.

It will be seen that this invention provides novel forms of high voltage, heavy duty circuit interrupters in which provision is made for caring for both heavy and light overloads and for l l0 overloads o! all intermediate values. Under a light overload a relatively restricted passage is provided for the blast o! arc extinguishing gas, whereas for a relatively heavy overload the expellable plug is expclled and a larger passage is provided for the blast of arc extinguishing gases. In this manner excessive building up of pressure internally oi' the device is prevented.

While a few of the possible arc extinguishing materials have been illustrated; it is to be understood that any suitable type posite structure and in the form shown consists of the fusible section, the strain wire, the retractable plunger and the flexible leader.

In all forms of the invention it is to be noted that the fuse tube has an arc channel therethrough which is divided into two portions, in one of which the blast of arc extinguishing gas is produced. The other portion of the arc channel provides a part into which a portion of the fuse link is retracted in all forms oi' the invention and, in the i'rm shown in Figures 2 and 6, this other portion provides a fuse link expulsion portion which has a true expulsion action.

. It is to be noted also that in all forms of the and over and refill units are supplied the user so that he may install the refill units without returning the tube to the factory. On the other hand, in the form of the invention shown in Figures 6 and 7 it would be the The old tube would be used over and over again but it would le refused at the factory as distinguished from the other forms of the invention.

It is to be noted that the fusible section of the fuse link is kept in spaced relation to the gas liberatingy materia. It is to be noted that the fuse link heats up to a considerable degree when it is carrying somewhat near its full rated load. By having the fusible section spaced from the gas liberating means, there is less chance of rupturing the container carrying thegas liberating means than if the fusible section of the fuse link than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim: 1. A circuit interrupter comprising a body portion provided with an arc channel, interrupting means adapted to interrupt a circuit under overload and form an arc in said arc channel, gas liberating means adapted to liberate a gas when acted upon by an arc, said gas liberating means being spaced axially of said body portion from said interrupting means, said body portion being tubular and having a portion extending beyond said gas liberating means in a direction away from said interrupting means and having a permanently open end, and an expellable apertured plug through which said arc is foi-meuv and through which the liberated gas passes to extinguish said arc, said plug being normally posiv tioned and retained in said arc channel solely by friction, said plug remaining in place in said arc channel for moderate overloads to provide a restricted passage and being expelled on heavy overloads to provide a larger passage.

2. A circuit interrupter comprising a body portion provided with an arc channel, interrupting means adapted to interrupt a circuit under overload and form an arc in said arc channel, gas liberating means adapted to liberate a gas when acted upon by an arc, said gas liberating means being spaced axially of said body portion from said interrupting means, said body portion being tubular and having a portion extending beyond said gas liberating means in a direction away from said interrupting means and having a permanently open end, said gas liberating means being located within said arc channel, and an expellable apertured plug Athrough which said arc is formed and through which the liberated gas passes to extinguish said arc, said plug being normally positioned and retained in said arc channel solely by friction, said plug remaining in place in said arc channel for moderate overloads to provide a restricted passage and being expelled on heavy overloads to 'provide a larger passage.

Zi. A circuit interrupter comprising a body portion provided with an are channel, interrupting means adapted to interrupt a circuit under overload and form an arc in said arc channel, gas liberating means adapted to liberate a gas when acted upon by an arc, said gas liberating means being spaced axially of said body portion from said interrupting means, said body portion being tubular and having a portion extending beyond said gas liberating means in a direction away from said interrupting means and having a permanently open end, means for leading an arc into proximity4 to said gas liberating means, and an expellable apertured plu-g through which said arc is formed and through which the liberated gas passes to extinguish said arc, said plug being normally positioned and retained in said arc channel solely by friction, said plug remaining in place in said arc channel for moderate overloads to provide a restricted passage and being expelled on heavy overloads to provide a larger passage.

4. A circuit interrupter comprising a. body portion provided with an arc channel, interrupting means adapted to interrupt a circuit under overload and form an larc in said arc channel, gas liberating means adapted to liberate a gas when acted upon by an arc, said gas liberating means being spaced axially of said body portion from said interrupting means, said body portion bein-g tubular and having a portion extending beyond said gas liberating means in a direction away from said interrupting means and having a permanently open end, a retractable plunger for leading an arc into proximity to said gas liberating means, and an expellable apertured plug through which said arc is formed and through which the liberated gas passes to extinguish said arc, said plug being normally positioned and retained in said arc channel solely by friction, said plug remaining in place in said arc channel for moderate overloads to provide a restricted passage and being expelled on heavy overloads to provide a larger passage.

5. A circuit interrupter comprising a body portion provided with an arc channel, means dividing said arc channel into a iirst and a second portion, a fuse link in said arc channel having a fusible section located in the first portion of said arc channel and extending through the sec ond-portion of said arc channel, gas liberating means located in the ilrst portion of said arc channel adapted to liberate gas when acted upon by the arc incident to the blowing of said fuse link, and means tending to draw said fuse link outwardly from the second portion of said arc channel, the second portion of said arc channel having an expulsive action-` in the event the arc is not extingushed by the gas liberated in the ilrst portion of said arc channel.

6. A circuit interrupter comprising a body portion provided with an arc channel, means dividing said arc channel into a first and a second portion, a fuse link in said arc channel having a fusible section located in the iirst portion of said arc channeland extending through the second portion of said arc channel, lgas liberating means adapted to liberate gas when acted upon by an arc, said gas liberating means being spaced axially of said body portion from the fusible section of said fuse link, and meansA tending to draw said fuse link outwardly from the second portion of said arc channel, the second portion of said arc channel having an expulsive action in the event the arc is not extinguished by the gas liberated in the iirst portion of said arc channel.

'1. A circuit interrupter comprising a body portion provided with an arc channel, means dividing said arc channel into a rst and a second portion, a fuse link in said arc channel having a fusible section located in the iirst portion of said arc channel and extending through the second portion of said are channel, gas liberating means adapted to liberate gas when acted upon by an arc, said gas liberating means bein-g spaced axially of said body portion from the fusible section of said fuse link, biased plunger means for drawing the arc incident to rupture of said fuse link into proximity to said gas liberating means, and means tending to draw said fuse link outwardly from the second portion of said arc channel, the second portion of said arc channel having an expulsive action in the event the arc is not extinguished by the gas liberated in the ilrst portion of said arc channel.

8. A circuit interrupter comprising a body p01'- tion provided with an arc channel, gas liberating means within said arc channel adjacent one end of said arc channel, said gas liberating means adapted to liberate gas when acted upon by an arc, a cap normally closing the end of said arc channel and having a weakened portion adapted to be ruptured by gas pressure to permit the central portion of said cap to be blown off, and an expellable apertured plug located in said arc channel and normally restricting said arc channel for moderate overloads and adapted to be blown from said arc channel through the opening in said cap resulting from the blowing oil:- of the central portion of said cap, the blowing of said plug from said arc channel occurring on heavy overloads.

9. A circuit interrupter comprising a body portion provided with a channel; a renewable reiill unit adapted to be positioned in said channel and comprising a sleeve, a retractable conductor, a fuse link including a fusible section connected to said conductor, an expellable apertured plug carried by said sleeve and adapted to be blown therefrom on heavy overloads, and gas liberating means in said sleeve spaced axially of said refill unit sleeve, a fiber sleeve positioned in the Other end 2,179,342 Muller 1 with the`rst mentioned bore, closure means at gas when acted upon by the arc incident to blowsaid other end defining an arcing chamber exing of the fuse; and retracting means detachably 1 teriorly of said bores, a conductive rod extending connected to said conductor. through said bores to said chamber, and a fuse 10. A circuit interrupter comprising a body por- 5 section in said chamber electrically connected to tion provided with a channel extending through said rod, said rod being movable out of said bores to be positioned in said channel and comprising a RALPH H. EARLE.

sleeve, a fuse link including a fusible section and ROALD H. AMUNDSON.

a retractable conductor, an expellable apertured 10 plug carried by said sleeve and adapted to be REFERENCES CITED blown therefrom 0n @Navy Overloads and Sas 11b" The following references are of record in the erating means in said sleeve adapted to libe'ae me of this patent:

gas when acted upon by the arc inciden o blowing of the fuse; and retracting means lo- 15 UNITED STATES PATENTS cated externally of the channel of said body por- Number Name Date tion for moving said conductor to elongate the 1,614,014 Murray Jan 11, 1927 arc- 1,743.322 Conrad 1 Jan. `14, 1930 11. A renewable rell unit for a circuit inter- 1,952,734 Ten Brook Mar 27, 1934 rupter, said unit comprising an insulating outer zo 211841495 Linden June 22, 1937 sleeve, a container positioned in one end of the 2,091,424 Tplett Aug 31, 1937 sleeve and dening a bore disposed axially of the 2,091,430 Conrad Aug. 31, 1937 NOV. 7, 1939 of said outer sleeve and dening a bore coaxial 2,269,130 Schultz Jan. 6, 1942 

